Far-IR heterojunction lasers tunable to 46.2 μm

The construction and testing of heterojunction diode lasers operating at 46.2 microns is reported. Single crystals of 80-percent PbSe/20-percent SnTe were grown from the vapor phase and annealed in metal vapor to invert the conductivity type and reduce the carrier concentration to 10 to the 17th to 10 to the 18th/cu cm; a wide-gap p-type epitaxial layer was deposited by photostimulated gas-phase epitaxy to fabricate the laser structures; and 300-500-micron resonators were produced by cleaving the crystals along the (100) planes. The laser output was studied with a Perkin-Elmer monochromator during 4-microsec-pulsed pumping at a repetition frequency of 100 Hz. it is found that the output frequency varied from 46.2 to 24.3 microns as temperature increased from 6 to 78 K. Sample output spectra at these temperatures are shown. It is suggested that further increases in output wavelength may be obtainable by reducing the carrier concentration or imposing a magnetic field.